“I climbed halfway up Mount Mitchell.”

“Tonight’s chicken will be cooked half-way.”

“We had a beautiful wedding. Never did sign the marriage license.”

There are no bragging rights associated with doing half of what you set out to do. If you turned in half an assignment to a professor, you’d be lucky to get a C. You could get an F.

And so it goes with the COVID-19 vaccine – unless you got the single-dose Johnson & Johnson vaccine. If you got one dose of Moderna or Pfizer, you’re halfway protected. But for how long? Scientists don’t know.

Physician assistant Becky DeCamillis

A week or two after the first dose, you’ll be about 50% protected, said Becky DeCamillis of Novant Health Infectious Disease Specialists in Winston-Salem on WBTV’s “Good Question” podcast on April 21. “But 50% isn’t great. It’s a shot in the dark. If you’re going to get one dose, I would not feel safe or protected.”

If you only got one dose, it’s not safe to take off your mask and hug your grandchildren, said DeCamillis, a physician assistant with a specialty in infectious diseases.

At a media briefing on April 27, Dr. David Priest, Novant Health’s COVID-19 expert, said, “Just under 30% of the U.S. population has been fully vaccinated. In fact, the Centers for Disease Control and Prevention has reported that nearly 8% of people have missed their follow-up appointment to receive their second dose. This equates to about 5 million people.”

“While one dose of the vaccine is good,” he continued, “I want to stress the importance of getting in for your second dose to ensure you get the full protection the vaccine offers, leading us to that herd immunity threshold.”

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Designed as a pair

The two mRNA vaccines were developed as a two-fer. And they were studied in clinical trials that way, too. For maximum efficacy, the Pfizer vaccines should be given three weeks apart, and the Moderna vaccines should be given four weeks apart.

But some people – lots of people, in fact – are deciding that once is good enough. That’s like deciding your halfway-cooked chicken makes an acceptable supper.

Side effects are expected

People who had a bad experience after the first vaccine may be especially reluctant to get the second shot. But lots of people experienced side effects – from a sore arm to flu-like symptoms that lasted for a few days.

These are “expected effects,” DeCamillis said. “When you look at the data from the trials, something like 70 to 80% of people studied had some sort of side effect.”

“I felt crummy after the first one,” she continued. But those effects were short-lived. It’s a small price to pay for inoculate yourself from a killer virus.

Not too late

If you missed your second vaccine appointment, don’t despair. “The CDC has given a little guidance on the matter,” DeCamillis said. “If you get that second shot within 42 days of the first shot, that’s great.”

“But even if you’re past those 42 days, make an appointment,” she said.

One is the loneliest number

The thing is, DeCamillis said, no one knows how long one dose provides up to 50% immunity. The vaccines weren’t studied that way. To get full immunity, you must get both doses.

To protect yourself, your family, your community, you need Nos. 1 and 2. We’re not going to achieve herd immunity if people stop at one dose. “Get the vaccine for yourself and your family,” DeCamillis said. “Do it to protect your community, your elderly neighbors, the folks down the street you may not even know who have underlying health conditions. Getting the second vaccine helps all of us.”

Just one warning

The only contraindication for the second dose is for people who had an immediate or severe reaction to the first. (Flu-like symptoms don’t count.) This would be shortness of breath, swelling of the tongue and lips, that sort of thing. If you had a severe reaction, ask your health care provider for guidance.

Be prepared

If you worry you may have a reaction to the second vaccine, have some Tylenol or ibuprofen on hand. But don’t take it until after you’ve had the vaccine. “If you take it beforehand as a precaution, we don’t know If it’ll tamp down your immune response,” DeCamillis said. After you’ve had the vaccine and it’s medically appropriate for you, it’s OK to take a pain reliever.

Still be cautious

Having both vaccines isn’t a ticket to a suddenly carefree life. DeCamillis is still advising her fully vaxxed patients to wear masks when you’re in public (outdoors, you can skip the mask if there’s not a big crowd) socially distance and avoid unnecessary travel.

“We’re at finish line,” she said. “We’re awfully close. But you could still get the coronavirus. No vaccine provides 100% immunity, although these vaccines come close. But if you’re fully vaccinated and do contract COVID, you’ll have a much less severe case.”

You wouldn’t fence in half your yard, would you? If you had a week’s vacation planned and your boss told you 2.5 days ought to be enough time, you’d argue your point. Don’t go around half vaxxed. Half a vaccination is like that undercooked chicken. Not good.